M3 Smart Motorway

Ultimate Client

Highways England

Main Contractor

Balfour Beatty

Type of Piling

124No Bearing

Diameter

900/1050mm

Depth

25m

Project Difficulties and Restrictions

As part of the Smart Motorway Upgrade to the M3, Martello were required to install large diameter piles at the new gantry positions, most of which, were in tight access situations of limited platform size and adjacent to a live motorway.
The ground conditions, of fine sand with a high water table, meant that the piles needed to be cased full depth to support the bore. The piles then had to be tremied and the waste water removed from site.
The project required the careful co-ordination of transport logistics to cover the inter-gantry moves along the network.

The Martello Solution

The Martello MP5000 rig had the ability to install the 900mm and 1050mm casings to the full depth at all pile locations, allowing construction to proceed in the planned methodology and sequence, despite the difficult ground conditions.
The MP5000 has a small footprint and has low ground bearing pressures allowing it to work on the small platform areas thereby saving the project time and money in their temporary works.

A mobile tank system incorporating settlement weirs was used to provide a water supply, and for the removal of sediment and the dispose of waste water.

Specific Project Features

This phase of the M3 Smart Motorway Upgrade required the construction of 124 No large diameter piles at multiple new gantry positions alongside the live motorway. The gantries required 900mm and 1050mm diameter piles of between (1 and 4 No), depending upon the type of gantry to be supported.
The piles usually required a full depth temporary casing which was installed with the piling rig and extracted with our own in-house designed casing extractor.

The project required logistical efficiency in the construction of piles and in the moving of equipment from site location to location.

Future Potential

With the ability to access smaller platforms on motorway schemes Martello piling rigs are successful in constructing large diameter piles with minimal disruption to the local environment, requiring smaller temporary works solutions.